<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <title>背景</title>
    <style>
        * {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
        }
        ul {
            list-style: none;
        }
        body {
            font: bolder 25px "Microsoft YaHei","Heiti SC",tahoma,arial,"Hiragino Sans GB","\5B8B\4F53",sans-serif;
            color: white;
        }
        .auto-center {
            width: 1000px;
            margin-left: auto;
            margin-right: auto;
        }
        .full-center {
            min-width: 1000px;
        }
        .text-center {
            text-align: center;
        }
        .clearfix::after {
            content: '';
            display: block;
            clear: both;
        }

        .top {
            background: #000079 url("https://img2.baidu.com/it/u=1403977252,4044276651&fm=253&fmt=auto&app=138&f=JPEG?w=679&h=500")left top /cover no-repeat;
        }
        .top>.auto-center {
            line-height: 100px;
            background-color: rgba(0,0,0,.5);

        }
        .banner {
            background: #003E3E url("https://img0.baidu.com/it/u=1811701003,4165153230&fm=253&fmt=auto&app=120&f=JPEG?w=1280&h=800") center /cover no-repeat;
            line-height: 300px;
        }
        .main {
            margin-top: 20px;
            background: #467500 url("./images/1.png");
        }
        /*基于浮动实现两栏布局，左边200px，右侧自动填充剩余空间*/
        .content-one {
            position: relative;
            height: 500px;
        }
        .content-one>.left {
            width: 200px;
            background-color: #613030;
            line-height: 500px;
            /* float: left; */
            position: absolute;
        }
        .content-one>.right {
            /* 思考，right为绝对定位是否可以实现两栏布局？ */
            margin-left: 200px;
            background-color: #336666;
            line-height: 300px;
        }

        /*基于浮动实现栏栅布局*/
        .content-tow {
            margin-top: 10px;
        }
        .content-tow>.list-item {
            float: left;
            width: 250px;
            height: 150px;
            box-sizing: border-box;
            background-color: #CAFFFF;
            background-size: contain;
            background-position: center;
            background-repeat: no-repeat;
            text-align: center;
            line-height: 150px;
            color: black;
            border: 1px dashed #ccc;
        }

        /* 基于浮动实现三栏布局，左固定200px，右固定250px，中间自适应宽度（填充剩余空间） 
        注意：中间一栏必须放到最后
        */
        .content-three {
            margin-top: 20px;
            position: relative;
            height: 300px;
        }
        .content-three>.left {
            position: absolute;
            width: 200px;
            left: 0;
            top: 0;
            /* float: left; */
            line-height: 300px;
            background-color: #F9F900;
        }
        .content-three>.right {
            position: absolute;
            width: 250px;
            right: 0;
            top: 0;
            /* float: right; */
            line-height: 300px;
            background-color: #A5A552;
        }
        .content-three>.middle {
            background-color: #5CADAD;
            margin-left: 200px;
            margin-right: 250px;
        }

        /* 基于浮动实现三栏布局，左固定200px，右固定250px，中间自适应宽度（填充剩余空间） 
        使用父级外边距实现
        */
        .content-four {
            margin-top: 20px;
            padding-left: 200px;
            padding-right: 250px;
        }
        .content-four>.left {
            width: 200px;
            float: left;
            line-height: 300px;
            background-color: #F9F900;
            margin-left: -200px;
        }
        .content-four>.right {
            width: 250px;
            float: right;
            line-height: 300px;
            background-color: #A5A552;
            margin-right: -250px;
        }
        .content-four>.middle {
            background-color: #5CADAD;
        }
        
        .footer {
            margin-top: 20px;
            background-color: #642100;
            line-height: 200px;
        }

        .fixed-ad {
            position: fixed;
            width: 100px;
            height: 300px;
            right: 20px;
            top: 50%;
            margin-top: -150px;
            background: #4D0000 url("https://tpc.googlesyndication.com/simgad/17371016686948028154?sqp=4sqPyQQ7QjkqNxABHQAAtEIgASgBMAk4A0DwkwlYAWBfcAKAAQGIAQGdAQAAgD-oAQGwAYCt4gS4AV_FAS2ynT4&rs=AOga4qnNb_psIDjzxDXDvxySskllK06_2Q") center/cover no-repeat;
            
        }

        .other {
            margin-top: 30px;
            background-color: #FF60AF;
            border: 1px dashed #ccc;
            position: relative;
        }

        .other .bottom {
            position: absolute;
            bottom: -10px;
            left: 20px;
            right: 20px;
            background-color: #B15BFF;
        }
    </style>
</head>
<body>
    <div class="top full-center">
        <div class="auto-center text-center">top</div>
    </div>
    <div class="banner text-center full-center">
        banner
    </div>
    <div class="main auto-center">
        <div class="content-one">
            <div class="left text-center">
                left
            </div>
            <div class="right text-center">
                right
            </div>
        </div>
        <ul class="content-tow clearfix">
            <li class="list-item" style="background-image: url(https://tse4-mm.cn.bing.net/th/id/OIP-C.1MOvhYr7-PNCCFY1w5yIzAHaEo?rs=1&pid=ImgDetMain)">list-item1</li>
            <li class="list-item" style="background-image: url(https://pic4.zhimg.com/v2-5290caf1f5c8c270e6da56b0361c9e1b_r.jpg)">list-item2</li>
            <li class="list-item" style="background-image: url(https://tse3-mm.cn.bing.net/th/id/OIP-C.neU_lyZXZpazGKjZXAlGywHaEK?rs=1&pid=ImgDetMain)">list-item3</li>
            <li class="list-item" style="background-image: url(./images/2.png)">list-item4</li>
            <li class="list-item" style="background-image: url(https://ts1.cn.mm.bing.net/th/id/R-C.31df3a5a2d8462228734f95d459883e2?rik=7EE6TeWDk%2f%2bctQ&riu=http%3a%2f%2fwww.quazero.com%2fuploads%2fallimg%2f140303%2f1-140303214331.jpg&ehk=SpI7mz%2byLqOkT8BL79jcd3iCtQYNFlBHQzbtF1p0vuQ%3d&risl=&pid=ImgRaw&r=0)">list-item5</li>
            <li class="list-item" style="background-image: url(https://img1.pconline.com.cn/piclib/200807/22/batch/1/5836/1216741512734nnouustae4.jpg)">list-item6</li>
            <li class="list-item" style="background-image: url(https://www.euweb.cn/wp-content/uploads/2016/12/302636-106.jpg)">list-item7</li>
            <li class="list-item" style="background-image: url(https://n.sinaimg.cn/sinacn10116/600/w1920h1080/20190326/2c30-hutwezf6832339.jpg)">list-item8</li>
        </ul>
        <div class="content-three clearfix">
            <div class="left text-center">
                left
            </div>
            <div class="right text-center">
                right
            </div>
            <div class="middle text-center">
                middle
            </div>
        </div>
        <div class="content-four clearfix">
            <div class="left text-center">
                left
            </div>
            <div class="right text-center">
                right
            </div>
            <div class="middle text-center">
                middle
            </div>
        </div>
    </div>

    <div class="other auto-center">
        <div>content</div>
        <div>content</div>
        <div>content</div>
        <div>content</div>
        <div>content</div>
        <div class="bottom text-center">title</div>
    </div>

    <div class="footer text-center full-center">
        footer
    </div>

    <div class="fixed-ad text-center">ad</div>

    
    <div style="position: fixed;
    top: 200px;
    left: 50%;
    margin-left: 500px;
    width: 50px;
    height: 150px;
    background-color: #ccc;">版心固定</div>
</body>
</html>